High-frequency generating and amplifying system



H. PAULI Dec. 31, 1929.

HIGH FREQUENCY GENERATING AND AIIPLIFYING SYSTEM 7 2 Sheets-Sheet. 1

Filed July 11, 1924 RAW" m ..I 4, Jm M w Dec. 31, 1929. H. PAULI 1,741,710

HIGH FREQUENCY GENERATING AND AMPLIFYING SYSTEM Filed July 11, 1924 2 Sheets-Sheet. 2

A TTORNE Y.

Patented Dec. 31, 1929 UNITED STATES PATENT OFFICE HEINRICH PAULI, OF BERLIN, GERMANY, A SSIGNOR TO THE FIRM DR. ERIGH F. HUTH GES. M. B. 11., OF BERLIN, GERMANY HIGH-FREQUENGY GENERATING AND AMPLIFYIN G SYSTEM Application filed .Tu1y 11, 1924, Serial No. 725,356, and in Germany July 13, 1923.

This invention relates to high frequency oscillating and amplifying systems, and has utilized in my invention.

Fig. 2 is acircuit diagram of an oscillating or amplifying system embodying my invention.

Figs. 3 and 4 are curve diagrams illustrating the wave shape of the oscillations produced by the oscillating system shown in Fig. 2.

Figs. 5 and 6 are diagrams illustrating modifications of my invention.

Fig. 7 illustrates the circuit arrangement embodying the principles of my invention in which a pair of tuned circuits are arranged in circuit with the control electrode; Fig. 8 illustrates a circuit embodying my invention wherein the generated oscillations. are filtered; and Fig. 9 illustrates the circuit arrangement for an electron tube system having a fourth electrode therein in accordance with the principles of my invention.

My invention is based on the discovery that if a three electrode discharge tube comprising an electron emitting hot cathode, a plate or anode, and a grid shaped control electrode, usually placed between the cathode and the plate, is so connected that the plate is maintained at a constant positive potential with respect to the cathode, while the potential of the grid with respect to the cathode is varied, the discharge path between the grid and the cathode behaves like a negative resistance. The current flowing to the grid or control electrode follows the course shown by curve I in Figure 1, while the current flowing in the plate circuit follows the course shown by curve I in said diagram. The abscissae in the diagram represent the voltage applied to the grid and the ordinates with the well known space-charge and satu r5 ration characteristics of such tubes. On the other hand, the current I in the grid circuit first increases up to the point a, and then decreases to the negative value b, and upon further increase of the grid voltage again so increases. It is found that the dropping part of the curve I corresponds to grid voltages which are less than the voltage of the plate with respect to the cathode.

This characteristic of the discharge tube may be utilized for the generation of oscillations by connecting in the circuit between the grid and the cathode a tuned resonant circuit.

Such arrangement is shown in Fig. 2 of the drawings in which a filamentary hot cathode 1, a grid electrode 2, and a plate anode 3 of a discharge tube 4 are connected to a source of voltage having a negative terminal 6 and a positive terminal 7 through a poten tiometer device or resistor 5, so as to permit the adjustment of the voltage applied to the plate and grid by means of the variable taps 9 and 11. the cathode being connected to the tap 8 of the potentiometer. A tuned oscillat- 30 ing circuit 10 is connected in 'the circuit between the grid 2 and the grid tap 11 and if, as explained before, the voltages applied to the grid 2 and to the plate 3 are suitably adjusted, the tuned circuit 10 will generate g5 undamped oscillations. The frequency of these oscillations depends principally on the adjustment of the tuned resonant circuit 10.

I have found that the wave shape of the.

generated oscillations depends on the adjust the values a and b of the curve I in Fig. e5

1, that is along the straight part of the grid current negative-resistance characteristic, the generated oscillations will have a substantially pure sine-waveshapeI However, if

the voltage is so adjusted that the current in the grid circuit varies during the oscillations along the curved portions of the grid characteristics between the points a, Z), or still more between the range a, b, the generated oscillations will considerably differ from the sine wave shape, and will be distorted, as illustrated in Fig. 3, showing depressions 12 and 13 which result from the fact that the current in the grid circuit has a positive characteristic within the ranges aa and b'b. By suitably enlarging the range of current variations in the grid circuit beyond the points a, b, of the curve L, Fig. 1, the depressions 12 and 13 may be so large that they cross the zero line as shown in Fig. at.

The resulting oscillation has thus in addition to the fundamental wave component, corresponding to the natural frequency of the oscillating circuit 10, a large double or triple frequency harmonic component which may be derived from the grid oscillating circuit by suitable filter circuits combined with the grid or plate circuit in any familar manner, the filter circuits being tuned to the frequency of theharmonic component.

The frequency and wave shape of the generated oscillations depends also on the temperature or electron emission of the cathode 1 and may be regulated by means of the filament-control resistor 14- connected in series with the cathode to the source of heating current 15. The frequency of the generated oscillations depends to a great extent on the adj ustmentof the filament control resistor 14-, in addition to the adjustment of the oscillating circuit 10.

A The output from the oscillating system also depends on the voltage applied to the plate and the operation of the tube may thus be controlled, in general, by the resonant circuit 10, the filament-heating control resistor 14 and the adjustment of the taps S, 11 and 9 leading to the cathode, grid and plate, respectively, or also, by varying the potential of the source applied to the terminals of the potentiometer resistor device 5.

antenna or a receiver is coupled with the plate circuit between the cathode and anode. The current oscillations in the grid circuit are reflected, as if in a mirror, in the plate circuit, the oscillations being either amplified or not, depending on whether the discharge tube operates on the steep increasing portion of the plate-current characteristic or on the flat por vtion thereof.

In such case, a suitable load devlce, such as a transmitting apparatus, an.

An arrangement of such character is shown in Fig. 5, wherein a discharge tube t is supplied from a current source indicated by the terminals 6 and 7, connected through choke coils 18 and 19 to the plate 3 and cathode 1, respectively.

The grid 2 may be maintained at a suitable potential with respect to the cathode by means of a source of voltage 20 and an ustable tap '21, the grid circuit including a tuned oscillating circuit 10, as in the arrangement shown in Fi 2. Between the plate?) and the cathode l is connected an output circuit including an output member 16 for observing the gener-' ated oscillations. As seen in the drawing. the output circuit is entirely independent of the input circuit including. the oscillating systemlO.

The alternating current generated may be influenced by Morse apparatus, microphones, or in any desired manner, and additional. electrodes may be introduced. For instance, a fourth electrode may be used as shown in 9 for modulating the oscillations or for starting and stopping the oscillations. The modulation by means of the fourth electrode 25 may be effected, for instance, by introducing between this fourth electrode and the cathode a controlling impulse (such as volt age or current through the tuned circuit 26) L The starting and stopplng of osclllatlons may" be produced with the aid of the fourth elec trode by applying to this electrode a voltage and then removing it or else by changing this voltage. A connection as shown in Figure 2 may be adjusted in such a manner that it produces, for instance, an audible oscillation, which can be heard or recorded in the apparatus represented by 16, which may be a headset. This apparatus may be connected (ll? rectly or indirectly in the circui of the third electrode 3. By modulating the circuit of the second electrode 2 by means of a received oscillation directly or indirectly through a rectifier, the following arrangement may be utilized.

An average preliminary voltage is applied to the second electrode 2 of such a magnitude that application of an additional voltage from the signal sets it in oscillation. The circuit 10 may also be tuned to a frequency slightly different from the received oscillation so that the two oscillations heterodyne with each other and produce an audible tuning in the circuit. 'An inaudible combination could be evidently also produced by super-position of two widely different frequencies. Such a combination may be utilized for further transmission or for reception. In the latter case a further heterodyning may be required. An

audible oscillation of this tube may be used for telegraphic transmission (tone sending). It is also possible to produce an audible oscillation of this type by means of the foumh electrode 25, and the oscillating circuit 26,

connected between this and one of the other electrodes and to different frequencies secured, which would result in an audible wave. Such an arrangement is illustrated in Fig. 9. It is further possible to arrange in such a way that the introduction of the extra oscillation acts as an amplifier to a received oscillation.

The possibility of frequency doubling has already been mentioned. This may be further utilized without generation of oscillations by the tube. In the arrangement of Fig. 2 the cathode heating is changed and the oscillations received in this circuit are amplified and modified as illustrated in Fig. 4. The oscillation of double frequency which is secured in this manner can then be utilized. This double frequency may be then combined with interfering frequency and an improvement in selectivity of reception thereby achieved.

In Fig. 6 the return connection from the device 16 is'shown connected to the slider 21 on battery 20 as distinguished from the circuit-arrangement in Fig. 5 where the device 16 connects between the cathode 1 and plate electrode 3.

In Fig. 7 I have shown independent tuned circuits 10, and 2526 connected in the input system.

In Fig. 8 I have shown means 28 in the output circuit for filtering the generated 0scillations.

In Fig. 9 the fourth electrode 25 has been illustrated connected in circuit with the tuned branch 26 to an adjustable contact 32 on the resistor 5 for impressing the required operating potential upon the fourth electrode.

l/Vhile I have described my invention in certain of its preferred embodiments, I desire that it be understood that modifications may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

I claim as my invention:

1. In a multi-wave generating system comprising an electron tube having a cathode and 'anode for producing an electron discharge stream, an output circuit connecting said cathode and said anode, auxiliary electrodes in the path of said discharge stream, means for applying electric potential to said electrodes with respect to said cathode and anode to produce a negative resistance characteristic in the path of said discharge stream between said cathode and said auxiliary electrodes and an oscillatory circuit in operative relation with and individual to each of said negative resistance paths to maintain electric oscillations for transfer to and superposition in said output circuit.

2. In a multi-wave generating system comprising an electron tube having a-cathode and a plate electrode for producing an electron discharge stream therebetween, an output circuit connecting said cathode and plate electrodes, a pair of auxiliary grid electrodes positioned between said cathode and plate electrode, a source of electrical potential, tuned circuits connected between each of said grid electrodes and said cathode, and means for applying different positive potential derived from said source to said plate electrode and each of said grid electrodes relative to said cathode to produce negative resistance effects between said cathode and each of said grid electrodes to maintain natural oscillations in the tuned circuits whereby said oscillations are superimposed in said output circuit.

In testimony whereof I affix my signature.

HEINRICH PAULI. 

